The present invention relates to a device for the hydraulic adjustment of the angle of rotation of a camshaft in relation to a crankshaft.
From DE 197 45 670 A1, a generic device is known for adjusting the angle of rotation of a camshaft in relation to a crankshaft of an internal combustion engine, said device being situated at the drive-side end of a camshaft mounted in the cylinder head of the internal combustion engine, and formed in principle as a hydraulic actuator that can be controlled dependent on various operating parameters of the internal combustion engine. This device essentially consists of a drive unit standing in a driven connection with the crankshaft via a traction device, as well as an output unit connected in rotationally fixed fashion to the camshaft and surrounded by the drive unit. The drive unit stands in a force-transmitting connection with the output unit of the device via a plurality of pressure chambers formed inside the device, which, upon alternating or simultaneous charging with a hydraulic pressure medium, effect a pivoting movement or fixing of the output unit in relation to the drive unit, and therewith of the camshaft in relation to the crankshaft.
In this device, the supply and conducting away of pressure medium to and from the pressure chambers of the device takes place from the camshaft-remote side of the device, via a separate distributor housing fastened to the cylinder head of the internal combustion engine, having a receptacle suitable for the insertion of an electromagnetic hydraulic valve for controlling the device and having a connecting flange suitable for the transmission of the pressure medium to the device. The receptacle of the hydraulic valve is connected to the connecting flange of the distributor housing via two pressure medium channels situated inside the distributor housing and has a connection to the pressure medium supply and to the pressure medium reservoir of the internal combustion engine.
For the transmission of pressure medium from the connecting flange of the distributor housing to the pressure chambers of the device, the device additionally has a cylindrical pressure medium adapter fastened to the camshaft-remote side of the output unit, formed with an axial through hole and clamped against the device by means of a central fastening screw when the device is screwed onto the camshaft. This pressure medium adapter has on its outer surface two annular grooves that are separated from one another by steel sealing rings that are suitable for the transmission of rotation and that stand in pressure medium connection with the pressure medium channels of the distributor housing, which open into the hollow cylinder of the connecting flange of the distributor housing, when said connecting flange of the distributor housing, formed with said hollow cylinder, is placed onto the pressure medium adapter of the device. A plurality of radial bores distributed around the periphery then open from these annular grooves into the axial through hole of the pressure medium adapter, in which, in a known manner, through a coaxially inserted pressure medium guide sleeve the pressure medium is supplied separately to the pressure chambers of the device or is conducted away from these chambers along the screw shaft of the central fastening screw and/or along the wall of the axial through-hole.
However, a disadvantage of this known device is that the pressure medium adapter that is additionally required for the transmission of the pressure medium is formed as a relatively expensive rotation transmitting part which, due to its constructive design, can be manufactured with high precision only through machining methods. However, such machining methods cause relatively long machine cycle times, and the required tools and apparatus, as well as the material used, result in a considerable manufacturing expense which in the end has turned out to be uneconomical and results in high manufacturing costs for the device. In addition, the pressure medium adapter fastened to the camshaft-remote side of the device increases the axial constructive length of the valve train of the internal combustion engine in such a way that in certain internal combustion engines such a supply of pressure medium to the device cannot be used due to narrow space conditions in the engine compartment of the corresponding vehicle.